The present invention relates to the field of electrical contacts. It relates to a contact element according to the introductory clause to claim 1.
Such a contact element, in which individual contact webs or contact plates are spring-mounted to a metal sheet band, is manufactured and sold by the applicant under the type designation xe2x80x9cMC contact lamella LACuxe2x80x9d, or is described in U.S. Pat. No. 4,456,325.
Lamellar contact elements or contact lamellae available primarily in two variants have proven themselves in the area of technology relating to electrical contacts for transmission of high currents. In one (single-piece) variant, the entire contact lamella is stamped out of a sheet strip, and molded in such a way as to yield a continuous row of individual contact webs projecting out of the sheet strip plane and sprung by torsion, which are interlinked by continuous lateral webs. If the contact webs are designed symmetrically to the longitudinal axis, the tolerance existing between two contact pieces that can still be bridged by the contact lamella depends on the width of the contact webs. The wider the webs twisted around their longitudinal axis, the higher the tolerance that can be bridged with them. Since the number of webs per length unit of contact lamella, and hence the number of contact points between the contact pieces, diminishes given an increasing width of the contact webs, the level of transmittable currents simultaneously decreases as the size of the bridgeable tolerance rises. To resolve this dilemma, it has already been suggested in the past (e.g., see EP-B1-0 520 950) that the contact webs be designed asymmetrically and interleaved in such a way that the bridgeable tolerance can be increased without having to change the number of webs per unit of length.
In the other variant as known from the production program of the applicant or publication cited at the outset, the functions of spring mounting and contacting are separated. Contact is established via individual, massive and electrically well conducting webs or plates (e.g., Cu or Ag), which are secured to a correspondingly stamped carrier band for purposes of fixation and spring mounting. Even though the functional separation of spring mounting and contacting and associated freedom in material selection in this variant enables an elevated flexibility in layout and simpler optimization of the contacting and resilience properties of the contact lamella, the previously used massive, essentially rectangular contact plates have made it impossible to arrive at higher bridgeable tolerances, and hence to expand the sphere of application of these contact lamellae, at a constant current transfer capacity.
Therefore, the object of the invention is to further develop a contact lamella consisting of a shared carrier band and numerous individual contact elements attached thereto in such a way that it allows a distinctly greater tolerance compensation without diminishing the current transfer capacity.
The object is achieved through, the entirety of features of the invention. The essence of the invention lies in the fact that individual elements are designed as interlaced contact bridges. Interlacing makes it possible to vary the effective width of the individual contact elements, and hence the bridgeable tolerance, within broad limits, without having to alter the periodicity or number per unit of length of the individual elements. Since the individual contact elements or contact bridges can be formed independently from the stamping of the carrier band, optimized geometries for the contact bridges can be realized in a simple manner.
A first preferred embodiment of the invention is characterized by the fact that the contact bridges are essentially V shaped with two free ends and a central bend lying in between, and that the free ends of the contact bridges are secured to the carrier band in such a way that their central bend lies at a predetermined height over the carrier band. In particular, the surface clamped by the V shaped contact bridges is inclined relative to the plane of the carrier band, and the carrier band is designed in such a way that the contact bridges attachxc3xa9 thereto can be resiliently moved toward the carrier band with their central bend. The V shaped bent bridges are easy to manufacture, and their central bend ensures a definite contacting.
The carrier band is preferably divided into individual band sections sequentially arranged in the direction of the longitudinal axis, wherein each band section is allocated a contact bridge, and each band section encompasses two spring-mounted arms that extend from a central web running in the central axis of the carrier band transverse to the longitudinal axis, whose two free ends are secured to the free ends of the accompanying contact bridges. This gives rise to particularly good resilience properties.
A second preferred embodiment of the contact element according to the invention is characterized by the fact that the contact bridges each consist of a wire section, and that, for attaching a contact bridge to the carrier band, the free ends of the contact bridge are routed from one side through recesses in the carrier band and clamped with the carrier band by bending the ends projecting through the recesses to the other side. The advantage to this is that the contact lamella can consist of very simple elements that can be rigidly bonded together without any special additional means.
One alternatively preferred embodiment of the invention is characterized by the fact that the contact bridges are made out of parts stamped out of sheet steel, that, for attaching a contact bridge to the carrier band, the free ends of the contact bridges each have a clamping foot with which it is clamped to the accompanying spring-mounted arm, that the contact bridges are essentially flat stamped parts, that the spring-mounted arms can be turned around their longitudinal axis to incline the contact bridges relative to the plane of the carrier band, and that the contact bridges have an embossed area for purposes of stiffening in the area of the central bend.
It has proven beneficial to arrange the contact bridges in the direction of the longitudinal axis with a contact spacing of several millimeters, preferably 2-8 mm, and to have the deflection of the central bend in the direction of the longitudinal axis relative to the attachment points of the contact bridges to the carrier band with the contact bridges inclined measure several millimeters, preferably about 5-10 mm.
Additional embodiments are described in the subclaims.